In present printing industries, the percentage of an offset printing is extremely large. In general offset printing techniques, such a system is used, for example, the image area of the resin composition having a thickness of several microns becomes lipophilic to receive an ink and the aluminum substrate whose surface has been subjected to a hydrophilization treatment becomes the non-image area to receive a water, whereby, the printing object is printed.
In that case, some properties are requested for the resin layer which becomes the image area, that is, they are as follows:
(1) application property, storage stability on production; PA1 (2) photosensitivity, developability, resolution, image distinguishability, long life of a developer on plate making; PA1 (3) lipophilicity, durability, chemical resistance, adherence with a substrate on printing, etc. PA1 (a) an alkali-soluble type binder resin, PA1 (b) a photosensitive substance, and PA1 (c) a dye; PA1 said binder resin (a) having an ampho-ionic group represented by the formula: ##STR3## wherein each R.sup.a is the same or different and respectively indicates H, CH.sub.3, C.sub.2 H.sub.6 or C.sub.5-8 alkyl group, R.sup.1 is H or a C.sub.1-20 alkyl group which optionally has a substituent or a functional group in a chain, R is a substituted or non-substituted C.sub.1-20 alkylene or phenylene group and A is --COO or --SO.sub.3. ##STR4## [wherein each R.sup.2 is the same or different and respectively indicates a C.sub.1-10 alkyl group which optionally has a substituent or a functional group in a chain, and R and A are as defined above] in a molecule and containing a resin having total acid value of 5 to 150. PA1 (i) a method comprising copolymerizing a polymerizable monomer having an ampho-ionic group with other ethylenically unsaturated polymerizable monomer to obtain an oligomer- or polymer-like resin, PA1 (ii) a method comprising esterifying an ampho-ionic compound as a starting material by polycondensation reaction to obtain an oligomer- or polymer-like resin, PA1 (iii) a method comprising adding an ampho-ionic group by modifying a resin to obtain an oligomer- or polymer-like resin and the like. PA1 the compound represented by the formula: ##STR6## [wherein each R.sup.7 is the same or different and respectively indicates H or a C.sub.5-8 alkyl group, R.sup.8 is H or a C.sub.7-10 alkyl group which may contain --SO--, --COO-- or --O-- group in a molecule, or a group represented by the formula: ##STR7## (wherein R.sup.7 is as defined above), and R.sup.9 is a C.sub.1-10 alkylene group which may be substituted with at least one C.sub.1-10 alkyl group]; PA1 the compound represented by the formula: ##STR8## [wherein each R.sup.10 is the same or different and respectively indicates H or CH.sub.3, R.sup.11 is a C.sub.1-20 alkyl or cycloalkyl group which may have at least one hydroxyl group and have --O-- or --COO-- group in an alkyl skelton, R.sup.12 is a C.sub.1-20 alkyl or cycloalkyl group which may have at least one hydroxyl group and have --O-- or --COO-- group in an alkyl skelton or H, or R.sup.11 and R.sup.12 bond together with N atom to form a hetero ring, R.sup.13 is a substituted or non-substituted alkylene group which is essentially represented by (CH.sub.2).sub.n (n is an integer of 1 to 6), and A is as defined above] and the like, as described in Japanese Patent Kokai Nos. 53-123899, 53-125996, 55-47651 and 55-47652. In addition to the above compounds, there can be used commercially available compounds such as N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl)-ammonium-betaine, ##STR9## N,N-dimethyl-N-methacrylamidopropyl-N-(3-sulfopropyl)-ammonium-betaine, ##STR10## 1-(3-sulfopropyl)-2-vinylpyridinium-betaine ##STR11## and the like (all of them are commercially available from RASCHIG AG.). PA1 (I) carboxyl group-containing monomer (e.g. acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc.), PA1 (II) hydroxyl group-containing monomer (e.g. 2-hydroxyethyl acrylate, hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methallyl alcohol, etc.), PA1 (III) nitrogen-containing alkyl acrylate or methacrylate (e.g. dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, etc.), PA1 (IV) polymerizable amide (e.g. amide acrylate, amide methacrylate, N-methylolacrylamide, diacetone acrylamide, etc.), PA1 (V) polymerizable nitrile (e.g. acrylonitrile, methacrylonitrile, etc.), PA1 (VI) alkyl acrylate or methacrylate (e.g. methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-butyl methacrylate, isopropyl methacrylate, 2-ethylhexyl acrylate, etc.), PA1 (VII) isocyanate group-containing monomer (meth)acryl isocyanate, isocyanateethyl methacrylate, etc.), PA1 (VIII) glycidyl(meth)acrylate, PA1 (IX) polymerizable aromatic compound (e.g. styrene, .alpha.-methylstyrene, vinyltoluene, t-butylstyrene, etc.), PA1 (X) .alpha.-olefin (e.g. ethylene, propylene, etc.), PA1 (XI) vinyl compound (e.g. vinyl acetate, vinyl propionate, etc. ), PA1 (XII) diene compound (e.g. butadiene, isoprene, etc. ) , PA1 (XIII) compound obtained by reacting a compound having a functional group which reacts with the above monomer (e.g. monomer produced by the reaction of hydroxyl group-containing monomer (II) with isocyanate compound, monomer produced by the reaction of carboxyl group-containing monomer (I) with glycidyl group-containing compound, etc.) and the like. PA1 [wherein R.sup.16 is an alkyl group which may have a substituent which does not reacts with an epoxy group, M is alkali metal ammonium group, and B is as defined above] PA1 at a chain terminal group to obtain a modified epoxy resin wherein a part of the terminal group of said epoxy resin is converted into the formula: ##STR14## [wherein all substituents are as defined above] In proportion to an equivalent of the ampho-ionic group of the epoxy resin, hydrophilic nature of the modified epoxy resin is enhanced. PA1 [wherein R.sup.19 is a substituent which may have a substituent which does not reacts with an epoxy resin, and B and M are as defined above] PA1 to obtain a modified polyether type epoxy resin wherein a part of the terminal group of said polyether type epoxy resin is converted into the formula: ##STR17## [wherein all substituents are as defined above] PA1 (1) Buffer effect of the ampho-ionic group: The effect is well known from the fact that the ampho-ionic substance is used as a buffer having buffer action. PA1 (2) Intensity of ionic character of the ampho-ionic group: PA1 (3) Ionic structure of the ampho-ionic group: An amino group part and an acid group part are liable to form an intramolecular counter ion structure in a molecule, or they are also liable to form an intramolecular counter ion structure between molecules.
Among them, developability and long life of a developer (i.e. even if the resin content in a developer becomes high by repeating developing operations, it's developability maintains the same quality as that obtained in the case of using a fresh developer) is considered to be important in view of practical use.
However, a conventional composition comprising an alkali-soluble type binder resin has a disadvantage that life of a developer is still insufficient and, therefore, a developer is deteriorated in a short period of time, which results in precipitation of the resin in the developer.